The present invention generally relates to a reinforced ceramic structure. More particularly, the invention is directed to a reinforced ceramic casting using composite rope. The addition of composite rope has now been found to provide a reinforced ceramic casting having substantially increased tensile strength. By virtue of the thermal expansion rate of the composite rope being substantially the same as the ceramic material, the reinforced ceramic casting with increased tensile strength remains integral at elevated temperatures.
In general, ceramic castings are low in cost, non-shrinking, and temperature tolerant. Ceramic castings have been used for years in the metal forming and glass forming fields and are presently being used for tooling and dies where composite parts and assemblies are fabricated for subsequent curing in an autoclave or oven and where metal parts are superplastically formed or diffusion bonded. Ceramic castings have tremendous strength in compression, but are weak in tension and prone toward breakage. In the prior art, to overcome this deficiency, the ceramic cast tool was usually formed very thick which makes the tool heavy and difficult to handle and uses excess material.
Other techniques have been tried in the past to increase the tensile strength of the ceramic castings. Some of these were addition of metal rods, metal needles, chopped fiberglass, and chopped graphite fiber. However, for various reasons these approaches have not been successful. Ceramic castings containing metal rods were subject to detached bonds at elevated temperatures due to the difference in thermal expansion between the metal rods and the ceramic casting material. Castings containing metal needles were prone to warp when subjected to thermal cycles and the tensile strength was not significantly improved. Chopped fiberglass and graphite fibers did not significantly improve the tensile strength because of the lack of a bond between the fiber and the surrounding ceramic material.